Chap 8 part 1

Question 1

how many membranes does the nuclear envelopes contain

Answer 1

2 membranes

Question 2

What are Lysosomes?

Answer 2

they carry transport protiens and hydrolytic enzyemes that get released by proteolytic cleavage to breakdown macromolcules

Question 3

What is the endo membrane system?

Answer 3

the
- Rough and smooth ER
- golgi appartaus
- endosomes
- lysosomes
- vacuoles

materials are passed down all along them

Question 4

What is the Biosynthetic pathway

Answer 4

proteins are synthesized in the ER and get modified in the Golgi apparatus then transported to various destinations

Question 5

Secretory pathway

Answer 5

proteins are synthesized in the ER and are secreted form the cell
- constitutive secretion
- regulated secretion

Question 6

Constitutive secretion

Answer 6

the materials made by the ER are constantly discharged by secretory vesicles

Question 7

regulated secretion

Answer 7

the materials made in the ER are stored in vesicles until stimulated to release

Question 8

Subcellular fractionation

Answer 8

homogenization which means you want to maintain the activity of the organelles of interest then centrifugation

Question 9

Differential centrigugation

Answer 9

separating by size/density by changing the rates of sedimentation

Question 10

Density gradient centrifugation

Answer 10

first isolated by differential then further separated by a sucrose gradient

Question 11

what needs to get out of the nucleus?

Answer 11

-mRNA
- mRNP
- protiens

Question 12

The 3 primary characteristics of microscopy

Answer 12

detect - find the object
resolve - distinguish it from another
magnify - make it bigger

Question 13

the relationship between wavelength and resolution

Answer 13

the smaller the wavelength, easier it will be able to be perturbed therefore detected by a small object

Question 14

Three factors to increase resolution?

Answer 14

• increasing angular aperture (allows for more light)
• high refractive index (allows more light to enter objective lens)
• small wavelength

Question 15

What is the effect of resolution on different wavelengths in relation to ABBE equation

Answer 15

shorter wavelength makes the distance between the 2 points can be resolved is smaller

Question 16

What are the limitations of light miscopy

Answer 16

the samples must be fixed and stained in order to be visual
fixation- preserved
staining- added for colour and differentiating

Question 17

The principles of fluorescence microscopy

Answer 17

light is absorbed at one wavelength and emitted at an longer one

Question 18

What does a dichroic mirror do in fluorescence microscopy

Answer 18

allows light of a certain wavelength to pass through, while light of other wavelengths is reflected

Question 19

Indirect labeling using antibodies

Answer 19

when a secondary isotope antibody with the fluorochrome will attach to primary antibody that is connected to the antigen

Question 20

Direct labeling using antibodies

Answer 20

the primary antibody has a fluorochrome on it and is directly connected to the antigen

Question 21

What is green fluorescent protein?

Answer 21

it comes from a oxidized chromophore of the chemiluminescent jellyfish
(oxidization occurs at 65-67 per-tyr-gly in the primary sequence)

Question 22

what is a pulse chase experiment?

Answer 22

Placing a cell in a solution of radioactive amino acids (the pulse), allowing it to be absorbed and incorporated into the enzymes synthesized by the ribosomes of the cell. Then washing away the radioactive amnio acids and replacing it with clean ones (the chaser)

This was done with sliced pancreatic cells to determine where the secretory proteins were synthesized and the path they follow to the site of discharge

Question 23

What is a cell free system?

Answer 23

they have been broken up and don’t contain full cell and are used to identify the roles of the proteins.

Question 24

What is Translation?

Answer 24

when a ribosome reads the mRNA to create a protein

Question 25

what is translocation?

Answer 25

movement of the genetic information

Question 26

What is co-translational translocation?

Answer 26

when the secretory protein is transported into the ER lumen while being synthesized by a ribosome

Question 27

what is post-translational translocation?

Answer 27

when the secretory protein is transported after being synthesized by a ribosome

Question 28

a secretory protein to undergo co translation is detected by...?

Answer 28

a signal sequence of 6-15 stretch of hydrophobic amnio acid residues on the nascent polypeptide

Question 29

steps of the secretory protein synthesis

Answer 29

- usually takes place co-translational 1) a signal recognition particle (SRP) attaches to the signal sequence of the nascent protein and the large ribosomal unit 2) then the SRP docks on the SRP receptor on the ER membrane 3) the ribosomal unit and the nascent polypeptide is handed to the translocon ( a protein channel embedded in the ER membrane 4) the signal sequence gets recognized and degraded and translation and translocation continue until the protein is released into the lumen of the ER

Question 30

how is an integral membrane protein synthesized

Answer 30

is it the same as secretory protein except a hydrophobic stop transfer sequence somewhere along the protein will cause translocation to stop but translation will continue

Question 31

what is the oligosaccharide precursor and how is it formed?

Answer 31

1) 2 GlcNAc and 5 mannose residues are adde to the cystolic face one at a time 2) they are flipped to the luminal side by the dolichol phosphate 3) they are added to an asparsgine residue on the nascent polypeptide in a tripeptide sequence ( Asn-X-Ser/Thr)

Question 32

what is a UPR?

Answer 32

Unfolded protein response - an accumulation of misfolded proteins in the ER as signal to make more chaperones and/or slow the rate of newly synthesized proteins

Question 33

what is a ERAD

Answer 33

they are ER associated degration proteins and they remove improperly folded proteins from the Er to the cystosol to be degraded. -This is called dislocation or reterotranslocation